For North Carolina, injury-plagued 2011-12 will be remembered around Chapel Hill as a season of "What if?" Its offseason begins with, "What now?"

Sophomore wing Harrison Barnes, junior power forward John Henson and sophomore point guard Kendall Marshall all are entering the NBA draft, the school announced Thursday. Add them to 7-footer Tyler Zeller, who is graduating, and the Tar Heels lose four-fifths of the starting lineup that led them to the NCAA regional finals.

Another player, reserve forward James Michael McAdoo, is pondering his decision this weekend, though his father said Wednesday he expects the freshman forward to be back in a UNC uniform next season.

"It's a great day for three youngsters who are taking another step toward their ultimate goal of playing professional basketball," coach Roy Williams said in a statement. "On a very small stage, it's a sad day for me because I won't get to coach them again. All Tar Heel fans will miss them greatly, as well."

Barnes, a first-team All-ACC selection, averaged 17.1 points this season, but leaves with a somewhat mixed legacy. Known for his clutch game winners as a freshman, he could never quite live up to all of the expectations that followed him as the No. 1 recruit in the nation. He struggled in his final four NCAA tournament games, making only 20 of 61 shot attempts. But he did qualify to have his jersey honored in the Smith Center rafters as a member of the NABC All-America second team. He said he will continue to pursue his degree and stressed in a statement how much he loves UNC.

"Chapel Hill is a special place,'' Barnes said in the statement. "Over the past two years I've enjoyed every single moment of my Tar Heel experience. The road we took to reach the Elite Eight in 2011 and again in 2012 were great team accomplishments. I am thankful to UNC fans, my teammates, and to have played for Hall of Fame Coach Roy Williams and the entire coaching staff. Now it's time for the next course of my journey."

When the 6-foot-11 Henson opted to return to school last season, he said he wanted to repeat as ACC Defensive Player of the Year while expanding his all-around game. He did both. Henson added a solid jumper and hook shot to his repertoire, showing overwhelming growth from his freshman season -- when he struggled so much he found himself on the floor with the walk-ons at the end of a couple of games. Even while missing three postseason games and finishing the season at less than 100 percent because of a sprained wrist, he averaged 13.7 points and 9.9 rebounds. He also leaves with 279 career blocks, second most in UNC history. He, too, said he plans to work toward finishing his degree.

"It's tough to leave because I love my teammates, coaches and UNC," Henson said in the statement. "I wish we'd been able to bring our fans a national championship, but it wasn't meant to be. I am proud of what we accomplished, especially the last two years. ...

"I can't say enough about how much I've enjoyed my experience in Chapel Hill. This was a big decision and it will be a big change, but I'm ready."

Marshall set the ACC single-season record for assists this season, but in the final month of his college career, he proved he could do more than pass. He scored in double figures in his last six games before a fractured right wrist sidelined the lefty for UNC's final two NCAA tournament outings (including Sunday's loss to Kansas). He leaves as UNC's all-time leader in assist average (7.96 per game), and as a fan favorite for the way he loved to pass first. He also won the Cousy Award, given to the nation's top point guard, on Thursday.

"It's been the greatest two years of my life," he said in the statement. "I have always put the team before myself and I am extremely proud of what we've accomplished. My life-long dream has been to play basketball at the highest level possible and I feel now is my greatest opportunity to fulfill this goal. I will always be a Tar Heel at heart and I will carry the experiences that I've had here both on and off the court with me for the rest of my life."

ESPN.com analyst Chad Ford currently ranks each of the trio among the top 17 NBA draft prospects.

They will be replaced on UNC's roster by a four-man incoming freshman class ranked fifth by ESPN. Marcus Paige, a McDonald's All-American, likely will have to start at point guard now that Marshall is gone. Meanwhile, Brice Johnson and Joel James will need to add depth to a fairly inexperienced frontcourt, and small forward J.P. Tokoto joins a now-wing-heavy team that includes Reggie Bullock (UNC's only returning starter), Leslie McDonald and Dexter Strickland (both returning from knee injuries), and P.J. Hairston.

"I really look forward to watching Harrison, John and Kendall play in the NBA," Williams said. "I know they will be very successful. They have been and will always be great Tar Heels."